Paddlefish (Polyodontidae) are ray-finned fish that belong to the order Acipenseriformes. Along with sturgeons, they are one of only two living groups in this order (Acipenseridae). Their long rostrums, which give them their name, set them apart from other fish. Scientists think that this helps them use electroreception to find prey.
People have called paddlefish “primitive fish” because their group, Acipenseriformes, is one of the oldest groups of ray-finned fish to split off from all the other living groups. This happened over 300 million years ago. Paddlefish are almost only found in China and North America, both now and in the past.
Paddlefish Scientific Name
These fish are in the order of Acipenseriformes and the family Polyodontidae. Sturgeons are also in this order. Polyodon spathula is the scientific name for the American Paddlefish. It is the only species of paddle fish that is still alive. The Chinese Paddlefish, which was thought to be extinct around 2005, was in the genus Psephurus and was called Psephurus gladius by its scientific name.
Six different kinds of Paddlefish are known to have lived in the past. Four of them are only known from fossils. Three of those species were from North America, and one was from China. The Chinese Paddlefish went extinct not too long ago, leaving only the American Paddlefish.
The word “Polyodon” comes from Greek and means “many-toothed.” The word “spathula” comes from the word “spatula” and refers to the paddle-like shape of the creature’s rostrum.
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How Many Species Of Paddlefish Are There?
The only species that is still around is the P. spathula or American Paddlefish. In the sections that follow, you can learn more about this species. Until recently, there was only one other type of paddle fish left in the world: the P. gladius, or Chinese Paddlefish. The Chinese Paddlefish, which was only found in the Yangtze River basin, was bigger than the American species.
It was also called the Chinese swordfish and the elephant fish. Moreover, it was about 10 feet long on average. It could grow up to 23 feet long and weigh up to 1,000 pounds, making it one of the biggest freshwater fish in the world. The longest and heaviest fish ever caught was 9.8 feet long and weighed 661.4 pounds.
The Chinese Paddlefish was also very different from its American counterpart because it was a highly predatory piscivore, which means that it almost only ate fish. In contrast, the American species is a filter feeder that gets almost all of its food from zooplankton.
So, now you know what is a paddlefish? The Chinese Paddlefish went extinct in 2020. It was listed as Critically Endangered by the IUCN in 1996. The last time it was seen for sure was in 2003, and scientists think it went extinct between 2005 and 2010. In the 1970s, more than 25 tonnes were taken out of the water each year, which was too much. In 1981, when the Gezhouba Dam was built, it cut their population in half. This changed their migration patterns and stopped them from breeding upstream.
Not much is known about the American Paddlefish. The IUCN has called this species “vulnerable” since 2004. Its numbers have been decreasing for several reasons, and it has been wiped out from its former homes in New York, Maryland, Pennsylvania, Lake Huron, and Ontario, Canada.
Since 1992, it has been hard to sell these fish around the world. In the 1980s, there was a lot more poaching of this species because Iran couldn’t get beluga caviar from the Caspian Sea because of a trade embargo. Demand for alternatives, like caviar made from the eggs of Paddlefish and sturgeon, went through the roof, which put populations in danger.
The species is also in danger because zebra mussels, which are an invasive species, have taken over the Mississippi River. Like Paddlefish, zebra mussels are filter-feeders. They quickly ate up all the zooplankton in the water, which caused paddlefish populations to drop. Today, the species is protected at both the state and federal levels, and the CITES act also protects it.
Today, the American Paddlefish is mostly found in 22 U.S. States in the Mississippi River basin. From New York to Montana and south to the Gulf of Mexico, you can find them.
Appearance: How Does A Paddlefish Look Like?
The American Paddlefish, from now on just called the paddle fish, is an ancient freshwater fish with a skeleton made of cartilage. It is related to the sturgeon. Its smooth skin is usually grey or green, and on average, the fish is about 5 feet long and weighs about 60 pounds. But some paddlefish can get as big as 7.2 feet long and 200 pounds on average.
The longest Paddlefish ever caught was 7.1 feet long, had a girth of 45.5 inches, and weighed more than 198 pounds. It was caught in Iowa in 1916.
The eyes of these primitive fish are small and not well developed. Their mouths are wide, and their snouts are long and paddle-like. Technically, the snout is called a “rostrum,” and it is an extension of the head. Its hair cells called the ampulla, have electroreceptors that can pick up on electrical fields that indicate the presence of food, which is usually zooplankton.
In fact, these receptors are sensitive enough to pick up on the movements of each of a zooplankton’s appendages, making it easier for them to find food. The paddlefishes also have sensory pores on about half of the surface of their bodies, which help make up for the fact that they can’t see well.
What eats Paddlefish? Due to their size, these fish don’t have many natural enemies. Lampreys, on the other hand, live off of them. Most of the time, a single lamprey only hurts the fish. But sometimes, more than one lamprey will attach to a paddlefish at once, which usually kills the Paddlefish.
What does a Paddlefish eat? So, what do Paddlefish eat? Most of the time, these fish eat zooplankton by filtering them out of the water. But they have also been known to eat small insects and their larvae and small fish.
Paddlefish Reproduction and Lifespan
The American Paddlefish is a fish that lives for a long time. On average, it lives for about 30 years. They are not sexually mature until they are older. On average, girls become sexually mature between the ages of 7 and 10, but some don’t until they are 16 or 18. Most boys become sexually mature around age 7, but some don’t until they are 9 or 10 years old.
This fish gives birth to its young in late spring. The temperature, water flow, and gravel substrate have to be just right. If these things aren’t just right, they might not spawn at all. Males are thought to spawn every year or every other year, while females do so every two or three years.
These fish swim upstream to lay their eggs. It’s not clear where exactly they migrate, but they have been seen to travel more than 2,000 miles in a river system. As mass spawners, the females put their eggs on bare gravel and rocks simultaneously when the males put out their sperm.
Fertilization happens outside of the egg, and the eggs stick to rocky surfaces. On average, it takes about seven days to hatch. The young are then carried downriver, where it grows up in deep ponds of fresh water.
Can You Eat Paddlefish?
So, are Paddlefish good to eat? Historically, Paddlefish have been used in place of sturgeon when seeking a food source for both meat and caviar. Natural populations of Paddlefish were once widespread in the Mississippi River basin and surrounding Gulf Coast drainage, where they were exploited for their high-value, boneless meat and roe sold as caviar.
What Is Special About Paddlefish?
The American Paddlefish has evolved specialized adaptations, such as filter feeding, making it a highly derived species of fish. Tens of thousands of sensory receptors cover its rostrum and cranium, allowing it to detect schools of zooplankton, its main food supply.
Are Paddlefish Dinosaurs?
The North American Paddlefish is the oldest living fish species in the world. It predates the dinosaurs, according to fossil evidence (300 million years).
Can You Keep Paddlefish As Pets?
Paddlefish, like sturgeons, are not suited for aquarium confinement. They have a high nutritional requirement, a high risk of rostral injury, and a huge adult size. Juveniles raised at a hatchery may occasionally be available for purchase at pet stores, but you should fight the urge to bring one home.
What Do I Feed My Paddlefish?
Even though certain Paddlefish are omnivores, the majority of their diet consists of zooplankton. Mayfly naiads and water fleas are two of their favorite foods among the crustacean zooplankton they consume.
Parvaiz Yousuf is a senior SEO writer and editor with an experience of over 6 years, who also doubles up as a researcher. With an MSc zoology degree under his belt and possessing complete Search Engine Optimization (SEO) knowledge, he works as a science journalist for a US-based website and Asian Scientist (A Singapore-based magazine). He also works as Director of Wetland Research Centre, Wildlife Conservation Fund YPJK since 2018. Besides, he has several publications to his name on cancer biology and biochemistry in some reputed journals such as Nature & International Journal of Molecular Sciences, & magazines such as Science Reporter, BUCEROS BNHS, and has an abiding interest in ornithology. He also worked as a Research Associate for JK Policy Institute.